Can someone give me the simple 411 on layers. Why are they used, how are they beneficial, what sorts of things are/can be created with using. What are they most used for?

Thanks

Layers are good for editing a particular piece of a photo/picture. There good for isolating objects. For example, suppose you have a picture of your family and you want to move someone around. With windows paint you can't move a person around the picture, but with layers (photoshop) you can move the person around the picture by just selecting the layer the person is located on and just drag them to a different position.

Hope that helps.